1. Field of the Invention
The present invention relates to printed circuit boards and, more particularly, to printed circuit boards having traces defined on the side edges thereof.
2. Description of the Related Art
As printed circuit board technology and chip mounting techniques have advanced, there has been an increasing need for chip mounting versatility. For example, there has been a desire to provide a means by which plastic leadless chip carrier (PLCC) sockets could be selectively converted to receive pin grid array (PGA) chips. Furthermore, there has been a desire to adapt surface mount boards to receive PLCC chips or to be interconnected with another surface mount board (mother board, daughter board, for example). Even further, there has been a desire to provide a means by which PLCC chips may be stacked in parallel.
It has been proposed to provide traces on the side of the printed circuit board for providing electrical connections between a PLCC socket and an adaptor for a different chip or another board. In accordance with that proposed configuration as illustrated in FIGS. 1A and 1B, slots 10 are made in a broad board which slots are then plated so as to define a metal layer along a portion of the side edges of the of the board. The gaps between slots are then severed along lines 12 so as to define a board having side edges which are at least in part defined by a metal plate. Cuts 14 (see FIG. 1B) are then made with a saw blade or drill at spaced locations along each metal plate so as to define discrete metal traces 16 on the side of the board. Traces 16 are sized and disposed so as to provide the necessary electrical connections with the leads of the PLCC socket.
The foregoing proposed tracing structure had the significant disadvantage that the surface defined traces could be easily ripped, chipped, delaminated, or removed which cuts 14 are made and in use.